前言：
对linux服务器做过漏洞扫描的都知道，常常服务器会被扫出一大堆关于openssh的漏洞，诸如下面这些，而其中的原因就是因为openssh版本比较低。于是就需要升级openssh的版本。下面就来解决一下这些问题。网上关于openssh升级版本的教程很多，但在实际过程中总会出现这样那样的问题，导致升级失败，甚至会导致ssh无法连接，本篇综合各类教程，并搭建了相应的靶机进行实操，亲测成功！也算是对这些漏洞的修复画一个句号。
流程：
安装前，可以使用ssh -V以及openssl version查询一下当前版本：
[root@localhost openssl-1.1.1l]# ssh -V OpenSSH_7.4p1, OpenSSL 1.0.2k-fips 26 Jan 2017 [root@localhost openssl-1.1.1l]# openssl version OpenSSL 1.0.2k-fips 26 Jan 2017
1，安装telnet
先查看原服务器有无安装telnet：
rpm -qa | grep telnet
如果在返回中没有telnet-server，就代表并未安装telnet服务端，执行下面操作即可。
直接安装这三个软件：
yum -y install telnet telnet-server xinetd
进行一些配置：
systemctl enable xinetd.service
systemctl enable telnet.socket
启动telnet服务：
systemctl start telnet.socket
systemctl start xinetd
使用netstat -antpl | grep 23，如果有返回值，则说明安装成功
[root@localhost ~]# netstat -antpl | grep 23 tcp6 0 0 :::23 :::* LISTEN 1/systemd
配置telnet连接方式：
vim /etc/securetty
然后在下面添加这几行：
pts/0 pts/1 pts/2 pts/3
配置完毕之后，使用如下命令，会看到的是这样：
[root@localhost ~]# tail -5 /etc/securetty xvc0 pts/0 pts/1 pts/2 pts/3
在防火墙上开放23端口：
[root@localhost ~]# firewall-cmd --zone=public --add-port=23/tcp --permanent success
重启防火墙：
[root@localhost ~]# firewall-cmd --reload
success
查看防火墙上开放的服务：
[root@localhost ~]# firewall-cmd --list-services
dhcpv6-client ssh telnet
可以看到，其中有telnet了。
退出ssh，使用telnet远程连接，以下均是在telnet连接下的操作。
2，备份
[root@localhost ~]# cp -r /etc/pam.d /etc/pam.d.bak [root@localhost ~]# cp -af /usr/bin/openssl /usr/bin/openssl.old [root@localhost ~]# cp -af /etc/pki/ca-trust/extracted/openssl /etc/pki/ca-trust/extracted/openssl.old [root@localhost ~]# cp -af /usr/lib64/openssl /usr/lib64/openssl.old [root@localhost ~]# cp -af /usr/lib64/libcrypto.so.10 /usr/lib64/libcrypto.so.10.old [root@localhost ~]# cp -af /usr/lib64/libssl.so.10 /usr/lib64/libssl.so.10.old [root@localhost ~]# cp -arf /etc/ssh/ /etc/ssh_old
3，关闭selinux并重启：
[root@localhost ~]# vim /etc/sysconfig/selinux
将其中的SELINUX=enforcing改为SELINUX=disabled
重启并getenforce：
[root@localhost ~]# reboot [root@localhost ~]# getenforce Disabled
4，升级openssl
下载openssl：https://ftp.openssl.org/source
从该网站下载最新版本的openssl-1.1.1l.tar.gz
拖到linux中，或者wget https://ftp.openssl.org/source/openssl-1.1.1l.tar.gz也可。
[root@localhost ~]# ls openssl-1.1.1l.tar.gz
解压：
tar -zxvf openssl-1.1.1l.tar.gz
[root@localhost ~]# ls openssl-1.1.1l openssl-1.1.1l.tar.gz
进入openssl目录：
[root@localhost ~]# cd openssl-1.1.1l/ [root@localhost openssl-1.1.1l]# ls ACKNOWLEDGEMENTS CONTRIBUTING INSTALL os-dep apps crypto LICENSE README appveyor.yml demos ms README.ENGINE AUTHORS doc NEWS README.FIPS build.info engines NOTES.ANDROID ssl CHANGES e_os.h NOTES.DJGPP test config external NOTES.PERL tools config.com FAQ NOTES.UNIX util Configurations fuzz NOTES.VMS VMS Configure include NOTES.WIN
清理旧文件并安装依赖包：
[root@localhost ~]# yum remove -y openssl [root@localhost ~]# yum remove -y openssh [root@localhost ~]# yum install -y gcc gcc-c++ glibc make autoconf openssl openssl-devel pcre-devel pam-devel cpan [root@localhost ~]# yum install -y pam* zlib* perl*
检查文件并移走备份：
[root@localhost openssl-1.1.1l]# ll /usr/bin/openssl -rwxr-xr-x. 1 root root 555288 Aug 9 2019 /usr/bin/openssl [root@localhost openssl-1.1.1l]# mv /usr/bin/openssl /usr/bin/openssl_bak [root@localhost openssl-1.1.1l]# ls /usr/include/openssl [root@localhost openssl-1.1.1l]# mv /usr/include/openssl /usr/include/openssl_bak
编译安装：
[root@localhost openssl-1.1.1l]# ./config --prefix=/usr/local --openssldir=/usr/local/openssl && make && make install
再次安装：
[root@localhost openssl-1.1.1l]# ./config shared && make && make install
检查编译安装结果，如果输出为0，则代表安装成功：
[root@localhost openssl-1.1.1l]# echo $? 0
配置openssl：
[root@localhost openssl-1.1.1l]# ln -s /usr/local/bin/openssl /usr/bin/openssl [root@localhost openssl-1.1.1l]# ln -s /usr/local/include/openssl /usr/include/openssl [root@localhost openssl-1.1.1l]# ll /usr/bin/openssl lrwxrwxrwx. 1 root root 22 Sep 17 16:19 /usr/bin/openssl -> /usr/local/bin/openssl [root@localhost openssl-1.1.1l]# ll /usr/include/openssl -ld drwxr-xr-x. 2 root root 4096 Sep 17 16:19 /usr/include/openssl [root@localhost openssl-1.1.1l]# echo "/usr/local/lib" >> /etc/ld.so.conf [root@localhost openssl-1.1.1l]# echo "/usr/local/lib64/" >> /etc/ld.so.conf [root@localhost openssl-1.1.1l]# /sbin/ldconfig [root@localhost openssl-1.1.1l]# cp libcrypto.so.1.1 libssl.so.1.1 /usr/lib64
安装成功，查看openssl版本：
[root@localhost openssl-1.1.1l]# openssl version OpenSSL 1.1.1l 24 Aug 2021
5，升级openssh
下载openssh：https://openbsd.hk/pub/OpenBSD/OpenSSH/portable
这里下载最新版本：openssh-8.7p1.tar.gz
拖拽或者直接wget https://openbsd.hk/pub/OpenBSD/OpenSSH/portable/openssh-8.7p1.tar.gz均可。
[root@localhost ~]# ls openssh-8.7p1.tar.gz openssl-1.1.1l openssl-1.1.1l.tar.gz
解压：
[root@localhost ~]# tar -zxvf openssh-8.7p1.tar.gz
[root@localhost ~]# ls openssh-8.7p1 openssl-1.1.1l openssh-8.7p1.tar.gz openssl-1.1.1l.tar.gz
进入openssh目录：
[root@localhost ~]# cd openssh-8.7p1/ [root@localhost openssh-8.7p1]#
编译文件：
[root@localhost openssh-8.7p1]# ./configure --prefix=/usr --sysconfdir=/etc/ssh --with-md5-passwords --with-pam --with-ssl-dir=/usr/local/openssl --with-zlib=/usr/local/lib64 --without-hardening
最后应该为这个样子：
config.status: config.h is unchanged OpenSSH has been configured with the following options: User binaries: /usr/bin System binaries: /usr/sbin Configuration files: /etc/ssh Askpass program: /usr/libexec/ssh-askpass Manual pages: /usr/share/man/manX PID file: /var/run Privilege separation chroot path: /var/empty sshd default user PATH: /usr/bin:/bin:/usr/sbin:/sbin Manpage format: doc PAM support: yes OSF SIA support: no KerberosV support: no SELinux support: no MD5 password support: yes libedit support: no libldns support: no Solaris process contract support: no Solaris project support: no Solaris privilege support: no IP address in $DISPLAY hack: no Translate v4 in v6 hack: yes BSD Auth support: no Random number source: OpenSSL internal ONLY Privsep sandbox style: seccomp_filter PKCS#11 support: yes U2F/FIDO support: yes Host: x86_64-pc-linux-gnu Compiler: cc Compiler flags: -g -O2 -pipe -Wall -Wextra -Wpointer-arith -Wuninitialized -Wsign-compare -Wformat-security -Wsizeof-pointer-memaccess -Wno-pointer-sign -Wno-unused-parameter -Wno-unused-result -fno-strict-aliasing -fno-builtin-memset -fstack-protector-strong Preprocessor flags: -I/usr/local/openssl -I/usr/local/lib64 -D_XOPEN_SOURCE=600 -D_BSD_SOURCE -D_DEFAULT_SOURCE Linker flags: -L/usr/local/openssl -L/usr/local/lib64 -fstack-protector-strong Libraries: -lcrypto -ldl -lutil -lz -lcrypt -lresolv +for sshd: -lpam PAM is enabled. You may need to install a PAM control file for sshd, otherwise password authentication may fail. Example PAM control files can be found in the contrib/ subdirectory
检查输出结果：
[root@localhost openssh-8.7p1]# echo $? 0
为0说明编译正常。
安装：
[root@localhost openssh-8.7p1]# make [root@localhost openssh-8.7p1]# echo $? 0
[root@localhost openssh-8.7p1]# chmod 600 /etc/ssh/ssh_host* [root@localhost openssh-8.7p1]# make install
[root@localhost openssh-8.7p1]# echo $?
0
配置ssh并启动：
[root@localhost openssh-8.7p1]# echo "PermitRootLogin yes" >> /etc/ssh/sshd_config [root@localhost openssh-8.7p1]# grep "^PermitRootLogin" /etc/ssh/sshd_config PermitRootLogin yes [root@localhost openssh-8.7p1]# echo "UseDNS no" >> /etc/ssh/sshd_config [root@localhost openssh-8.7p1]# grep "UseDNS" /etc/ssh/sshd_config #UseDNS no UseDNS no [root@localhost openssh-8.7p1]# cp -a contrib/redhat/sshd.init /etc/init.d/sshd [root@localhost openssh-8.7p1]# cp -a contrib/redhat/sshd.pam /etc/pam.d/sshd.pam [root@localhost openssh-8.7p1]# chmod +x /etc/init.d/sshd [root@localhost openssh-8.7p1]# chkconfig --add sshd [root@localhost openssh-8.7p1]# systemctl enable sshd sshd.service is not a native service, redirecting to /sbin/chkconfig. Executing /sbin/chkconfig sshd on [root@localhost openssh-8.7p1]# chkconfig sshd on
移走原先服务，有报错可以无视：
[root@localhost openssh-8.7p1]# mv /usr/lib/systemd/system/sshd.service /home/ mv: cannot stat ‘/usr/lib/systemd/system/sshd.service’: No such file or directory
重启sshd：
[root@localhost openssh-8.7p1]# /etc/init.d/sshd restart Restarting sshd (via systemctl): [ OK ]
查看是否正常开放：
[root@localhost openssh-8.7p1]# netstat -antpl Active Internet connections (servers and established) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 0.0.0.0:111 0.0.0.0:* LISTEN 784/rpcbind tcp 0 0 192.168.122.1:53 0.0.0.0:* LISTEN 1804/dnsmasq tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 107261/sshd: /usr/s tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN 1309/cupsd tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN 1660/master tcp6 0 0 :::111 :::* LISTEN 784/rpcbind tcp6 0 0 :::22 :::* LISTEN 107261/sshd: /usr/s tcp6 0 0 :::23 :::* LISTEN 1/systemd tcp6 0 0 ::1:631 :::* LISTEN 1309/cupsd tcp6 0 0 ::1:25 :::* LISTEN 1660/master tcp6 0 2 192.168.145.139:23 192.168.145.2:1205 ESTABLISHED 1/systemd
查看版本：
[root@localhost openssh-8.7p1]# ssh -V OpenSSH_8.7p1, OpenSSL 1.1.1l 24 Aug 2021
使用ssh测试连通：
[C:~]$ ssh 192.168.145.139 Connecting to 192.168.145.139:22... Connection established. To escape to local shell, press 'Ctrl+Alt+]'. WARNING! The remote SSH server rejected X11 forwarding request. Last login: Fri Sep 17 17:17:26 2021 from 192.168.145.2 [root@localhost ~]#
6，关闭并卸载telnet：
[root@localhost ~]# systemctl disable xinetd.service Removed symlink /etc/systemd/system/multi-user.target.wants/xinetd.service. [root@localhost ~]# systemctl stop xinetd.service [root@localhost ~]# systemctl disable telnet.socket Removed symlink /etc/systemd/system/sockets.target.wants/telnet.socket. [root@localhost ~]# systemctl stop telnet.socket [root@localhost ~]# netstat -antpl Active Internet connections (servers and established) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 0.0.0.0:111 0.0.0.0:* LISTEN 750/rpcbind tcp 0 0 192.168.122.1:53 0.0.0.0:* LISTEN 1502/dnsmasq tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 1245/sshd: /usr/sbi tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN 1191/cupsd tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN 1509/master tcp 0 36 192.168.145.139:22 192.168.145.2:15925 ESTABLISHED 1996/sshd: root@pts tcp6 0 0 :::111 :::* LISTEN 750/rpcbind tcp6 0 0 :::22 :::* LISTEN 1245/sshd: /usr/sbi tcp6 0 0 ::1:631 :::* LISTEN 1191/cupsd tcp6 0 0 ::1:25 :::* LISTEN 1509/master
结束！